Reliability of a cycling time trial in a glycogen-depleted state

Currell, Kevin; Jentjens, Roy L. P. G.; Jeukendrup, Asker E.

doi:10.1007/s00421-006-0305-7

Cited by 12 publications

(11 citation statements)

References 20 publications

(29 reference statements)

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“…Despite this, in trained and habituated cyclists, it is suggested that a familiarisation trial may not be needed. Currell et al (2006) reported no significant difference in CV between three repeated trials (4.5 and 3.8% between trials 1 and 2 and trials 2 and 3, respectively), and is in agreement with the study of Jeukendrup et al (1996) who found no learning effect in a group of well-trained cyclists.…”

Section: Discussionsupporting

confidence: 88%

“…Despite this, most remaining participants were consistent between tests, and demonstrated a level of reliability consistent with that of trained cyclists, as demonstrated by Jeukendrup et al (1996). Other time trial protocols have been evaluated and have suggested a CV as low as 1% (Laursen et al 2003;Palmer et al 1996;Smith et al 2001) though it has been suggested that a contributing factor in those studies was the feedback and encouragement given (Currell et al 2006). In the present study, participants were encouraged during each trial, but not informed of their performance in each trial until the study had been completed.…”

Section: Discussionmentioning

confidence: 84%

“…Despite the lack of extensive experience of cycling as an exercise mode and/or the laboratory testing environment, reliability of 3.4% (mean CV for the group using typical error) and 6.3% (CV of individual values) in recreationally active participants compares reasonably well with other studies evaluating similar types of test in trained cyclists. Literature examples include 3-4% in trained cyclists using a cycle ergometer (Jeukendrup et al 1996), 3.7% in adolescent cyclists (Montfort-Steiger et al 2005), and 3.8-4.5% in trained cyclists in a glycogendepleted state (Currell et al 2006). The pre-load exercise intensity used in the present study (65% of peak VO 2 ) is Jeukendrup et al 1996).…”

Section: Discussionmentioning

confidence: 98%

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Evaluation of a cycling pre-load time trial protocol in recreationally active humans

Sewell

McGregor

2007

Eur J Appl Physiol

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The need for greater sensitivity in exercise performance measures is of particular importance in nutritional intervention studies and such measures have been investigated in trained cyclists, but not in those who have no experience of laboratory testing and/or the need to pace their effort. The aim of the present study was to evaluate a mixed design approach (constant load then time-trial) endurance type cycle ergometer protocol using recreationally active participants not well accustomed to cycling. Seven participants including one female (age 25 +/- 5 years; body mass 74.4 +/- 9.3 kg; peak VO(2) 3.91 +/- 0.96 l) completed four repeat cycle tests. The test consisted of a "pre-load" (60 min at 65% of peak VO(2)) followed by a 20 min time trial (performance measure). Reliability for the performance measure was assessed by calculating the individual participant coefficient of variation (CV) and a mean CV for the group. Excluding a familiarisation trial, mean CV for the group was 3.4% (95% confidence interval between 2.0 and 10.1%). It is concluded that the performance test described can be used in recreationally active young adults with lower variation after one familiarisation trial. The protocol might be used to evaluate an intervention if changes in performance are expected to be greater than 3.4%, or greater than around 7% if a signal to noise ratio of 2: 1 was to be considered appropriate.

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Section: Discussionsupporting

confidence: 88%

Section: Discussionmentioning

confidence: 84%

Section: Discussionmentioning

confidence: 98%

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Evaluation of a cycling pre-load time trial protocol in recreationally active humans

Sewell

McGregor

2007

Eur J Appl Physiol

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“…Prior glycogen depletion produces a reliable measure of performance with metabolic characteristics for evaluating carbohydrate supplementation during endurance exercise (30). Whole-body muscle glycogen storage is about 150 mg in mice (22) and total glucose oxidation during endurance exercise is about 2 mg/min/mice (3).…”

Section: Discussionmentioning

confidence: 99%

Improved Swimming Pool Achieves Higher Reproducibility and Sensitivity to Effect of Food Components as Ergogenic Aids

Ishihara

Yamada

Mita

et al. 2009

J Nutr Sci Vitaminol

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Summary A previously developed current swimming pool for mice has been used to evaluate many food components that enhance endurance exercise performance. In this article, to improve reproducibility, reliability and sensitivity of this assay system, we improved the spout part to generate a uniform current and divided the pool into six lanes to avoid physical interference between swimming mice. The stability of the current flow was assessed by measuring the surface current speed and water volume from the spout part. Maximum swimming times of ddY and BALB/c mice were measured to assess the reproducibility of the maximum swimming time. The improvement in sensitivity compared to the original equipment was estimated under three physiological conditions: low carbohydrate diet feeding, low blood hemoglobin level, and carbohydrate supplementation during exercise. The new spout part improved uniformity and quick adjustment of surface current, yielding an increase of workload in a stepwise manner during swimming. Exercise workload was increased in proportion to surface current speed, as evidenced by cadence of kicks and serum lactic acid levels. The improved swimming pool showed higher reproducibility of swimming time until fatigue ( p Ͻ 0.0001). Correspondence between blood hemoglobin concentration and swimming time was improved in the swimming pool. The improved swimming pool yielded higher sensitivity for low carbohydrate diet feeding ( p Ͻ 0.0001) and carbohydrate supplementation during exercise ( p Ͻ 0.01) compared to the original swimming pool. The improvement of the swimming pool achieved higher sensitivity and reproducibility in assessing various diet and food components compared to the original swimming pool.

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“…This showed that there were no significant differences in time trial performance between galactose (mean 42.04 ± 1.4 minutes) and glucose (mean 41.05 ± 2.9 minutes). The use of a time trial protocol is physiologically valid (9) and is likely to detect small but potentially crucial differences. However, with a small sample size (n=8) this study may have lacked adequate statistical power (calculated to be ~0.3).…”

Section: Introductionmentioning

confidence: 99%

The Effect of Pre-Exercise Galactose and Glucose Ingestion on High-Intensity Endurance Cycling

O’Hara¹,

Carroll²,

Cooke³

et al. 2014

Journal of Strength and Conditioning Research

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This study evaluated the effects of the pre-exercise (30 minutes) ingestion of galactose (Gal) or glucose (Glu) on endurance capacity as well as glycaemic and insulinaemic responses. Ten trained male cyclists completed three randomised high-intensity cycling endurance tests. Thirty minutes prior to each trial cyclists ingested 1 litre of either 40g of glucose, 40g of galactose, or a placebo in a double blind manner. The protocol comprised: 20 minutes of progressive incremental exercise (70% to 85% maximal power output (W max )); ten 90 second bouts at 90% W max , separated by 180 seconds at 55% W max ; 90% W max until exhaustion. Blood samples were drawn throughout the protocol. Times to exhaustion were longer with Gal (68.7±10.2 minutes, P=0.005) compared to Glu (58.5±24.9 minutes), with neither being different to placebo (63.9±16.2 minutes). Twenty-eight minutes following Glu consumption, plasma glucose and serum insulin concentrations were higher than with Gal and placebo (P<0.001). Following the initial 20 minutes of exercise, plasma glucose concentrations increased to a relative hyperglycaemia during the Gal and placebo, compared to Glu condition. Higher plasma glucose concentrations during exercise, and the attenuated serum insulin response at rest, may explain the significantly longer times to exhaustion produced by Gal compared to Glu. However, neither carbohydrate treatment produced significantly longer times to exhaustion than placebo, suggesting that the pre-exercise ingestion of galactose and glucose alone is not sufficient to support this type of endurance performance.

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Reliability of a cycling time trial in a glycogen-depleted state

Cited by 12 publications

References 20 publications

Evaluation of a cycling pre-load time trial protocol in recreationally active humans

Evaluation of a cycling pre-load time trial protocol in recreationally active humans

Improved Swimming Pool Achieves Higher Reproducibility and Sensitivity to Effect of Food Components as Ergogenic Aids

The Effect of Pre-Exercise Galactose and Glucose Ingestion on High-Intensity Endurance Cycling

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